This invention is generally directed to a novel non-bubble forming dropper tip which is used to dispense fluids, such as medications and the like. More particularly, the invention contemplates a novel multiple-use dropper tip which is designed to control air bubble development and drop size when the occasional bubble is encountered while dispensing viscous, low density, often thixotropic fluids, such as liquid eye medications or the like.
In order to allow less frequent user applications and reduced rate of absorption by the body, medications for the eye are increasingly being formulated to provide sustained release into the eye. Viscous high film strength carrier vehicles used to deliver these medications can make uniform dose delivery by means of common, prior art dropper bottles difficult. These medications may be highly disposed to inadvertent generation of air bubbles, which in turn accumulate at the meniscus or even trap within the fluid body. These bubbles are often very reluctant to disperse once they have been formed.
A depiction of dispensing drops from a prior art dropper tip 20 is shown in FIGS. 6A-6Q. The dropper tip 20 is formed from a body 22 having an inner wall 24 which defines a conduit therethrough. The conduit is formed from a first cylindrical wall portion 26, which is connected to a larger diameter second cylindrical wall portion 28, which is connected to an even larger diameter third cylindrical wall portion 30. The transition between the first and second wall portions 26, 28 is not smooth and a sharp shoulder 32 is provided. Likewise, the transition between the second and third wall portions 28, 30 is not smooth and a sharp shoulder 34 is provided.
Bubble generation most often occurs during the aspiration phase of dispensing when the make-up air drives fluid back down the dropper tip 20 into the container 36. As is shown in FIGS. 6A-6Q, air returning quickly back down the conduit and encountering the sharp shoulders 32, 34 of the smaller-to-larger diameter transitions can cause bubbles to be formed if a film bridges across this transition edge resulting in a film covered aperture upon which the inrushing air will cause bubbles to be blown. Bubbles must be kept from blocking outward fluid flow paths where the bubbles can become entrained in the fluid and impair accurate drop formation.
A second prior art dropper tip 38 is shown in FIG. 7. This dropper tip 38 is formed from a body 40 having an inner wall 42 which defines a conduit therethrough. The conduit is straight and has a small diameter.
Conduit diameter is also important in controlling bubbles. A conduit which has a diameter that is too small will exhibit jetting and bubbling aspiration as shown in the prior art dropper tip 38 shown in FIG. 7
Moreover, in each of these prior art dropper tips 20, 38, the delivery tip surface 44 is rounded. The rounded surface 44 encourages the attachment of fluid thereto which can interfere with proper drop size, see FIGS. 6A-6Q.
The present invention provides a novel dropper tip structure which overcomes these problems and presents other features and advantages over the prior art which will become apparent upon a reading of the attached specification, in combination with an examination of the drawings.